NASA Administrator Charles Bolden is the last person you'd expect to drop the F-bomb in public, but when it comes to next month's test flight of the space agency's Orion deep-space capsule, he's willing to come perilously close.

"That's a big deal," Bolden told a luncheon audience last week at the annual Von Braun Symposium in Huntsville, Alabama. "As the vice president would say, and I'm not going to say it, that's a B.F.D."

So why does Bolden think Orion is a big freakin' deal? "It is the first time this nation has produced a vehicle intended to carry humans beyond Earth orbit, into deep space, in more than 40 years," he said. "More than 40 years! That's a B.F.D., OK?"

Bolden isn't the only one using strong language to describe the significance of Orion's first launch, known as EFT-1 or Exploration Flight Test 1.

"EFT-1 is absolutely the biggest thing that this agency is going to do this year. I may be partial, because it's in my area. ... This is really our first step in our journey to Mars," Bill Hill, NASA's deputy associate administrator for exploration systems development, told reporters on Thursday during a pre-mission briefing at Kennedy Space Center in Florida.

As ambitious as that sounds, Orion's EFT-1 is just one small step in a development effort that began eight years ago and currently costs $1 billion a year. The cone-shaped craft looks like a bigger version of the Apollo moonship of the 1960s, but it's not expected to be ready for astronauts until the 2020s.

Two-orbit trip

The EFT-1 test is scheduled for launch on Dec. 4 from Cape Canaveral Air Force Station's Launch Complex 37, next to Kennedy Space Center. The Orion test capsule will ride into space atop a United Launch Alliance Delta 4 Heavy launch vehicle and make just two orbits around Earth. One of the orbits will rise as high as 3,600 miles (5,800 kilometers).

Four and a half hours after launch, the craft will blaze back through Earth's atmosphere on a trajectory that should reduce its speed from 20,000 mph to 20 mph (32,000 km/h to 32 km/h). Along the way, the heat shield's temperature is expected to rise as high as 4,000 degrees Fahrenheit (2,200 degrees Celsius), which is hotter than molten lava.

Exploration Flight Test 1 is due to send a test Orion crew module as far as 3,600 miles from Earth.NASA

If all goes well, Orion will unfurl its parachutes, splash down into the Pacific Ocean and get picked up by a recovery ship — a scenario that echoes how the Apollo missions ended more than four decades earlier.

This time, no one will be aboard the craft. In fact, this Orion has no seats or display screens inside. But it does have plenty of cameras — plus about 1,200 sensors that have been placed to monitor all the stresses, strains and shocks that are felt inside and out during flight and splashdown.

In a sense, this flight is an early robotic rehearsal for what astronauts will experience when they go around the moon in the 2020s, or when they fly out and come back from an asteroid or Mars and its moons.

Tests can't be done on Earth

The mission is expected to demonstrate how the Orion jettisons its launch abort system after launch, measure how much radiation exposure astronauts would get as they fly through the Van Allen radiation belts, and show how smoothly the crew capsule separates from its service module before re-entry.

"Some of these events are difficult or even impossible to test on the ground," said Mark Geyer, NASA's Orion program manager.

But the launch abort system won't include the hardware that would fly the capsule to safety in the event of an emergency during the ascent. And most of the service module is merely a structural stand-in for hardware that the European Space Agency is supposed to provide for Orion. Geyer said the decision to put Orion to its first flight test without those elements was driven by the development schedule as well as cost.

Geyer said EFT-1 is costing NASA $370 million, which includes the price of the launch vehicle as well as "the stuff we throw away" during the flight — but not the Orion capsule itself, which will be reused in future tests. NASA is paying Orion's prime contractor, Lockheed Martin, to take the leading role in mission operations and recovery.

EFT-1 will also mark the first real-world run-through for the members of NASA's Orion mission control team, who have been practicing their procedures in a newly remodeled flight control room at Johnson Space Center in Houston. The final dress rehearsal is scheduled next week, said Orion flight director Mike Sarafin.

The road ahead for NASA

After EFT-1, NASA will analyze the data collected during the flight and feed that into the next test flight, currently set for late 2017 or 2018. That practice run, known as EM-1 or Exploration Mission 1, is set to send an uncrewed Orion craft around the moon and back — and it should mark the maiden launch of NASA's heavy-lift Space Launch System, which is currently under development.

"This rocket is designed to take Orion beyond the moon, and on to Mars," SLS program manager Todd May told reporters at NASA's Marshall Space Flight Center in Huntsville last week.

The first flight test with a crew on board, EM-2, is designed to carry four astronauts on a round-the-moon mission in 2021. After that, Orion-SLS missions are expected to lift off about once a year, leading to a rendezvous with an asteroid as early as the mid-2020s and a human mission to Mars and its moons in the 2030s. Other elements of NASA's exploration system, such as a habitation module for long-duration trips, are still on the drawing board or in the workshop.

"The space station is a great platform for proving out technologies, and we're doing that, getting ready for Orion in the long run," NASA's Hill said. "And obviously we need commercial crew. So basically, we need all three to be successful, and we're approaching it that way."